Alpha-Actinin 3 (ACTN3)| A Fast-Twitch-Muscle Fibers Support protein

Alpha-Actinin 3

Athletic performance is a complex human trait influenced by environmental parameters such as Diet, training, opportunity, and heritable factors, that is genetic makeup. Genetic factors determine 20%-80% of the variation in a wide variety of traits relevant to athletic performance, such as oxygen uptake, cardiac output and the relative proportion of fast and slow fibers in skeletal muscle. For the last decade, researchers have defined a large number of the individual genes underlying these influence, an effort highlighted in the annual publication of the human gene map for performance and physical fitness traits.
 One gene potentially associated with human physical performance is the ACTN 3 gene, which encodes the protein Alpha-Actinin3. This Protein forms part of the contractile ( sarcomeric) apparatus in the fast glycolytic fibers of human skeletal muscle- the fibers responsible for the generation of rapid, forceful contractions in activities such as sprinting and weightlifting- and is thought to perform specialized role important to the function of these fibers. The precise function of Alpha-Actinin3 are still unknown but are likely to include a structural role in the maintenance of muscle mechanical integrity and possibly other functions related to muscle signalizing and metabolism. Several years ago, one team identified a common genetic variation in the ACTN3 gene that results of an Arginine with a stop codon at amino acid 577. This variation creates two different versions of the ACTN3 gene, both of which are common in normal, functional version of a gene, whereas the 577 allele contains a sequence change that completely prevents the production of functional Alpha-Actinin3 protein.Because every human inherits two copies of the ACTN3 gene- one maternal and one paternal copy- there are three possible combinations of genotypes of 577 alleles.In individuals of Europian descent, less than a third of the population have two copies of the functional allele, whereas just over half population have one copy of each of the two alleles. Remarkably, the remaining 18% of the healthy Europian population, and more than a billion people worldwide- have two copies of the nonfunctional 577 variants, resulting in the complete deficiency of Alpha-Actinin3 protein in their skeletal muscle.